If you are truly looking for the best micrometer, then one thing you have to know is the type. It’s very important because it affects the success of your measurement. Since the micrometer is designed for specific purposes; not really a purpose though, taking a wrong micrometer will likely lead to unaccepted measurement.
For example, if you are going to measure the thickness of the cartridge neck wall, then you take a flat-anvil micrometer, it will be totally failed. However, if you use the ball micrometer, it’s the right one. Similarly, for measuring a piece of paper, then you take a V-anvil micrometer, it’s more preferable to use the flat-anvil type one.
There are various micrometer types available. The largest division is based on what side of the object that is measured. This classification has three divisions: inside, outside, and depth micrometers. Inside is designed to measure the internal diameter of an object. Outside is to measure the outside diameter, the thickness of something, and length. Depth is to measure the depth of holes.
Then, each division can be classified based on the anvil type and other aspects. In this classification, the types are wide. Further, the micrometers are divided based on how it works. Simply how the micrometer displays its reading: mechanical, digital, and dial.
Based on The Measurement It Can Handle
A. Inside Micrometer
The inside micrometers are designed in a way to measure the internal dimension of an object such as the inside diameter of a tube or hole. There are other sub-divisions of inside micrometer such as tubular, caliper-type, and bore micrometer. Starrett, Mitutoyo, and iGaging are some well-known brands that you can check out when you need to buy this type of micrometer.
| Type | To Measure |
|---|---|
| Caliper-type | Inside Diameter |
| Tubular | Inside Diameter |
| Bore | Inside Diameter |
| V-anvil | Outside Diameter |
| Blade | Outside Diameter |
| Bench | Outside Diameter |
| Laser Scan | Outside Diameter |
| Limit | Outside Diameter |
| Ball | Thickness |
| Tube | Thickness |
| Universal | Outside Diameter & Thickness |
| Depth | Depth |
1. Caliper-type Micrometer
At a glance, it looks like a caliper, but this one is more accurate and price. It can measure until the micron scale. Instead of anvil and spindle, these micrometers have jaws which are inserted inside the objects. The jaws are adjusted by the ratchet according to the space of the object.
2. Tubular Micrometer
These micrometers lack a C-frame and they are placed in the space to be measured. After that, they are extended to the desired length so that the micrometers meet the two edges of the object. Once they are secure, the readings can be taken.
3. Bore Micrometer
Bore micrometer or bore gauge is still the family of the inside micrometer. It’s useful to quantify the internal diameter of a hole or a cylindrical object such as an engine cylinder. It has no spindle, only anvil. The anvil extends until reaching the inside wall of the hole, then the readout can be taken. There are sub-categories of bore micrometer. They are available in the dial, mechanical, digital, one anvil, two anvils, and three anvils. Typically the range is 6 inches.
B. Outside Micrometer
Just like the outside vernier caliper, the outside micrometers are designed in a way to measure the external dimensions of objects. This type of micrometers is the most common type on the market. An outside micrometer is very suitable to measure outside diameter and thickness.
1. Flat Micrometer
This is the most commonly used of outside micrometer ever. They can be in digital and analog model. You can easily find it on any market. It has a flat surface both on the anvil and spindle. It’s a standard micrometer that has to be on your toolbox because of its wide uses, however, the best one is to measure the thickness and diameter.
2. V-Anvil Micrometer
It has V-shaped anvil which is specifically designed to measure the outside diameter of a ball object. V micrometer is truly able to lock the ball so that it can’t move even a little. It makes sure that the object can’t slip from during measurement. This V anvil together with the spindle allows them to secure the object in three touching points.
3. Blade Micrometer
The blade micrometer has a couple of blade-shaped anvil and spindle. It is designed to measure the groove diameter of keyways and shafts. The objects are screws and similar to it which has grooves on it.
4. Bench Micrometer
Bench micrometer is a micrometer that is set in a bench. It is typically so precise and accurate that many works use it for inspection. Its least count reaches 0.000050” or 0.002mm. Therefore, it’s great to use in a laboratory.
5. Laser-Scan Micrometer
Laser-scan micrometer employs a laser to measure the object with high precision and accuracy. It could measure with precision 0.000002″/0.00005mm. The precision is extremely wonderful. Typically it’s similar to bench type because it’s set up on a bench. It’s available in digital display and needs another additional tool to work with. The cost of a non-contact laser scan micrometer is also fantastic but it works amazingly.
6. Limit Micrometer
The limit micrometer has two sets of anvil and spindle. It works to examine whether an object is under range or not. For example, objects only pass the measurement if its diameter ranges in 1.001″ to 1.005″. You then adjust the anvil and spindle on the upper section sets apart 1.001″ in length and the lower section sets apart 1.005″ in length. Any object that you measure; they have to get measured with the two sections, if they are not oversized or undersized, they are not. Whereas they pass the measurement then they are what you want.
7. Ball Micrometer
Like its name, this micrometer’s anvil looks like a ball (spherical). It allows the anvil to touch only one point on the object. Surely, this improves accuracy. Therefore, ball micrometer is very useful to measure the thickness of wall tubes or wall rounded surfaces. It’s not rare that many people use ball micrometer for reloading.
8. Tube Micrometer
Tube micrometer is similar to ball micrometer in terms of the anvil stands vertically to the spindle. However, the anvil looks like a tube which is different than ball micrometer that looks like a ball. Tube micrometer is also best to use for measuring the thickness of cylindrical objects whether the thickness of all sides have been uniform or not. It’s also reasonable for reloading purpose.
9. Uni Micrometer
It means universal micrometer. You can replace the anvil with another one (interchangeable) which has a different shape and use. Uni micrometer is helpful if you are going to measure various objects with different shapes. However, its price is also amazing.
10. Long Throat Micrometer
The long throat micrometer has a great size C-frame. It’s great to measure the thickness of a piece of a metal plate because it allows you to reach the far point.
11. Disk Micrometer
One of the most useful functions of a disk micrometer is to measure the thickness of gear teeth.
C. Depth Micrometer
As the name suggests, the depth micrometers are designed to measure the depth of different holes and steps. They have different lengths of interchangeable rods which make them versatile enough to measure different depths.
So what is your preferred micrometer type to help you work with? Sure, it depends on the object and what object’s part you are going to measure. Whatever your measurement, micrometer types are available to serve you the possible accurate measurement.
Based on the How the Reading is Displayed
The micrometer reading is displayed in analog/conventional, mechanical counter, and digital. Some models provide more higher resolution reading by adding a vernier scale to its conventional reading. In some models, the digital micrometer come with a conventional way of reading as well.
Speed and convenience are values you can obtain from a digital micrometer. Even you can set the zero point at any position you want. However, its price may be expensive. And you have to prepare the battery backup and always check/inspect its accuracy with a certain length of gauge block. If the power is low, the reading may not be reliable.
The conventional model, on the other hand, will last forever if proper care runs. There is no battery required. However, turning the thimble can take time and several measurements can take more time.